1. Field of the Invention
The present invention relates to an information storage medium (or an information recording medium), an information reproduction device, and an information reproduction method.
2. Description of the Related Art
As such an information storage medium, there has been an optical disk called a digital versatile disk (DVD) capable of reproducing digital information using a focused light. Standards of the current DVD include read-only DVD-ROM standards, write-once DVD-R standards, rewritable-type (about 10000 times) DVD-RW, and rewritable-type (10000 times or more) DVD-RAM standards. Any standards have format standards which define a data structure recorded on an optical disk (information storage medium) of video information (video data, sub-picture data, and audio data, generically referred to as video objects) itself, and a data structure of management data for managing video information.
The read-only current DVD video standards simultaneously deal with a large number of languages, and multi-scene representation is possible such as multi-angle and multi-story. Additionally, there are varieties of menu screens, it is easy for users to directly access desired scenes, and the standards have formats capable of providing video content which is easily used by the users (see U.S. Pat. No. 5,636,200, and Japanese Patent No. 2,677,775, for example).
As described above, the read-only current DVD video standards have the formats capable of the video content easily usable by the users, but there has been a demand for improvements of the standards in order that the users may further easily use the content and content representing power may be further enriched for the users.
Moreover, there is a problem that authoring (preparation and edition of programs to be recorded in the DVD video disk) is complicated in order to provide the content easy to use by the users.
Parts of the current DVD video standards lacking in content representing power for the users, and parts difficult for the users to use or parts which are complicated in the authoring for providing the content easy to use by the users will be specifically listed.
[1] Difficult for the user to use. Alternatively, the authoring has been complicated in order to prepare the content easy to use by the users.
(A) Disadvantages with respect to a reproduction start position at a time when reproduction of a title is interrupted halfway to perform another processing, and the reproduction of the title is restarted.
(A1) The reproduction of video is interrupted, display is switched to menu or another video, and the reproduction cannot be restarted from the interrupted position.
The reproduction of a specific video title is interrupted halfway during the reproduction to switch to the menu screen,. bonus content is then reproduced halfway or to the end, and afterwards the video title interrupted halfway is to be reproduced. However, the content prepared by conventional DVD video standards cannot be reproduced only from a start position of the video title in many cases. This is because resume information (reproduction interrupted position information) of the previous specific video title is rewritten into position information of the bonus content in a stage in which the reproduction of the bonus content is started. A complicated authoring process is required in order to obtain the content such that the reproduction can be started from the interrupted position of the previous video title after the bonus content is reproduced halfway or to the end.
(A2) The reproduction cannot be started from a good place to start, when a game is to be resumed after the interruption of the reproduction in the game or the like.
In case of the “game” (e.g., role playing game) instead of the above-described video as the specific title, there is a request from a content provider that the game is to be started from an end of a chapter of the game, not from an interrupted position in a case where the game is resumed after returning to the menu screen. However, this request cannot be satisfied with the current DVD video standards.
(B) There is a portion difficult to use concerning language setting for display.
(B1) A menu description language code cannot be changed with a command which can be designated in the content, and the authoring is complicated.
In the current DVD video standards, the menu description language code M_LCD is set into SPRM(0) (0-th system parameter: 16 bits) of navigation data, and the value is stored in the memory of the information reproduction device. In the current DVD video standards, a command for changing the value of SPRM(0) does not exist in a command list which can be set in the content, and it is possible to change the value of SPRM(0) only by user designation under a special condition. Specifically, the value of SPRM(0) can be changed using a user operation function called Menu_Language_Select ( ) in user functions arranged in the information reproduction device, but there is a restriction that the user operation called Menu_Language_Select ( ) can be set only during the stopping of the operation of the information reproduction device. A screen for exclusive use is displayed to set the user operation using a remote controller.
The value of SPRM(0) cannot be changed with the command which can be set in the content in this manner. Therefore, a screen for selecting the menu description language code needs to be prepared with respect to a plurality of menu description language codes in the content (especially VOB data on menu information) so that any setting of the value of SPRM(0) can be handled. The authoring operation at the time of preparation of the content has been very difficult.
(B2) There is a danger that menu description language code information set by the user is deleted.
For example, supposing that a command capable of changing the value of SPRM(0) is newly added in order to solve problem (B1). Then, even when the user carefully sets a specific menu description language code (e.g., set Japanese to SPRM(0)), there is a danger that the value of SPRM(0) is automatically changed by the reproduction of the content. When the menu description language code is automatically changed by the command, the user feels dissatisfied. Additionally, a necessity to set the menu description language code again by the user is generated, and this causes a problem that burdens on the user increase.
[2] There is a place where a content representing power for the user is lacking.
(C) Disadvantage concerning seamless reproduction with respect to a still picture
(C1) A seamless reproduction between a moving picture and still picture is not possible with the current DVD video content.
The current DVD video assures the seamless reproduction of the moving picture (Movie Content), and connection/reproduction is seamlessly possible between different VOBs (or different titles) (without interrupting the screen of the moving picture halfway). On the other hand, for example, when the still picture displayed in a slide show (one display method with respect to the still picture, in which the displayed still picture is automatically switched) is switched to the moving picture, the seamless reproduction is not assured, and video or audio stands still halfway depending on the information reproduction device in some case. Reasons why the seamless connection is not assured at a time of the switching to the moving picture from the still picture with the current DVD video content are as follows.
i) In an extended system target decoder (E-STD) in which the seamless reproduction is assured, an access unit is defined in a moving picture object, and the values of a system time clock (STC: a clock value forming a standard) set to a separation unit, video decoder unit, sub-picture decoder unit, and audio decoder unit are switched in a boundary position of the access unit. On the other hand, the access unit cannot be defined with respect to the still picture in the current DVD.
That is, a picture continues to be output constantly continuously by a field unit of the moving picture, whereas the picture is only intermittently output in the still picture displayed, for example, in the slide show. In a data structure in a still picture object, a sequence end code (sequence_end_code) is arranged immediately after an I picture (intra picture) constituting a still picture in accordance with standards of moving picture experts group 2 (MPEG2). In the video decoder unit, when this sequence end code is detected, the decoding is stopped until the next I picture is input. Therefore, in the conventional DVD video, the access unit such as the moving picture cannot be set in a timing period in which the still picture is intermittently output.
ii) Switching between common parities has been permitted as a switching timing between the still pictures in the conventional DVD video. That is, after the previous still picture ends in a top field (or a bottom field), the next still picture is permitted to be started from the top field (or the bottom field). Therefore, when the still picture is switched to the moving picture halfway in a frame, the seamless connection is not performed, and there is a danger that the screen is disturbed at a switching end.
(C2) Multi-angle reproduction in which the still pictures are combined or multi-angle reproduction between the moving picture and still picture cannot be performed.
In the current DVD video, it is difficult to perform the multi-angle reproduction in which slide shows of still pictures (still picture content) are combined or the multi-angle reproduction in which the slide show of the still pictures is combined with the moving picture. When multi-angle reproduction handling content is forcibly prepared, the seamless reproduction is not assured with respect to the still picture. Therefore, multi-angled still pictures cannot be continuously reproduced (the still picture is stopped halfway without being continuously switched), or the screen stops halfway without being smoothly switched at the switching end between a screen of multi-scene and that of one sequential scene. In the moving picture, an interleaved unit (ILVU) is defined in which scattered arrangement is performed for each angle in an interleaved block, whereas the definition of the ILVU with respect to the still picture is not clarified in the current DVD video. A period until the switching of the screen is long in the still picture (the same still picture continues to be reproduced for a long time), and therefore there has not been a mechanism capable of displaying the corresponding still picture immediately after angle switching at present. Furthermore, as described in (C1), on detecting the sequence end code arranged immediately after the I picture corresponding to the still picture, a decode process of the video decoder unit is temporarily stopped until the next I picture comes. Therefore, the arrangement of the sequence end code is prohibited in video data in a cell constituting the interleaved block in the current DVD video standards.
(D) The seamless reproduction is not assured in VOB where the command by a cell unit is included.
In the DVD video of the current standard definition (SD), it is possible to designate the command by the cell unit in a program chain (PGC). This command information is recorded in a cell command region in program chain information (PGCI) which is a region where management information of the PGC is recorded. The cell command is executed at the time of the ending of the reproduction of the cell in which this cell command is set. Therefore, the reproduction of the next cell can be temporarily interrupted. Therefore, the seamless reproduction between the cells is not assured at the playback time of VOB including the cell command in the current SD DVD video.
(E) Disadvantage on highlight information
(E1) There is a deviation of a display period (set period) between highlight information and sub-picture.
A menu of the highlight information is displayed at the playback time of a video title image, and content can be prepared in such a manner that the user is can perform an interactive operation. In this case, it is necessary to switch the highlight information or to change the content of the highlight information in accordance with the content of the video title image being reproduced, and therefore precision of a display period or executable period of the highlight information is important. In the DVD video content of the conventional SD, a button displayed in the screen comprises a combination of two types of different streams of a sub-picture stream presenting the image of the button and a video stream including the highlight information required for executing the command designated by the button.
The effective executable period of the highlight information is determined by time information of start and end (PTM: presentation time), and completely coincides with a display period of the sub-picture for use mainly in subtitles. There is a problem that menu selection ends, when the sub-picture ends. Therefore, when a content maker is to prepare the content of the subtitles simultaneously combined with the menu, there are restrictions as to the preparation of the content. For example, the user has to select the menu within an effective (display) period of the sub-picture. The content maker cannot prepare the content as imaged, a degree of freedom is limited, and the content supplied to the user are forced to be limited.
(E2) A selection item image of the menu is not multicolored.
Since only a combination of 16 colors can be represented in the current SD DVD video content, a degree of appeal to the user is low, and multicolored representation cannot be performed.
(E3) A designated region of the highlight information cannot be set to a shape other than a rectangular shape.
The shape other than the rectangular shape cannot be set as the designated region of the highlight information in the DVD video content of the current SD, and it has not been possible to prepare the content having varieties of highlight information such as a triangular shape and a star shape.
(E4) The same button cannot be set with respect to a plurality of regions distant from one another on the screen.
The same button can be set only in an integrated region in the DVD video content of the current SD.
On the other hand, it is easy to link the same URL to a plurality of regions in the screen of PC or a homepage screen of internet, and the current SD DVD video content has been inferior to the PC screen or the homepage screen of internet.
(F) There is a problem that a background music discontinues at the switching time of the menu screen.
In the current SD DVD video content, audio information (background music) at a menu screen display time is attached to each menu. Therefore, every time the menu screen changes, the audio information accordingly changes.
The DVD video content of the current SD cannot satisfy a content provider's request that the background music is to be reproduced continuously without being interrupted, even when the menu is switched.
In this manner, the conventional DVD video standards have been required to be improved so that the user can further easily use the content, and the content representing power to the user is further enriched.
Moreover, to provide the content easy to use by the user, there is a problem that the authoring (preparation and edition of the program to be recorded in the DVD video disk) is complicated.